Polymer additives reduce fluid drag in turbulent flow

The study of turbulence in fluid dynamics has recently advanced in several new directions, and at the same time has gone a long way towards solving a problem: the uncanny efficacy of tiny amounts of polymer additives in reducing the drag between solids and liquids in turbulent flow. The phenomenon, which may well prove a boon to farmers and firefighters, has also begun to help improve our understanding of a fundamental problem in fluid dynamics, the structure and onset of turbulence. According to François Frenkiel (David W. Taylor Naval Ship Research and Development Center), the new directions include the recognition of coherent phenomena intermixed with quasistatistical effects. New visualization techniques on the one hand, and high‐speed computing methods (for data analysis as well as modelling) on the other, have brightened the outlook in the field. Much of the recent work in drag reduction is summarized in a recent volume of The Physics of Fluids, containing the proceedings of a 1976 meeting.